its too dry hence the brown patches. I wouldn't do anything too drastic to it at the moment. Other than dig out the weeds using a knife/thin trowel. and lightly rake at the moss.
Watering it would help also but depends on if you have any hose pipe bans/water meter costs etc. After some decent rain it will green up again.

When it has recovered it would be a good idea to set your mower blades higher. Very short grass is more vulnerable to dry spells. Even if you have problems with watering you can always throw the washing up water etc onto it. If your waste pipe is accessible you can even divert your washing machine water onto it (if you use an eco brand) I did this quite a lot where we lived before but can't reach here. No point in putting any chemicals on it until its growing again. Obviously this is only helpful if you have a fairly small lawn...
Its surprising how quickly it will green up when it does eventually rain.

Hi Jackie: The ground looks very parched and the ground is like baked clay. It needs TLC. Scarify is a good start to get some oxygen down to the root and help break up the clods. I would get a pic axe in there and break up the sod just turn in over. Lay down a couple inches of compost and work it in. Rake out all the weeds and what looks like crab grass. Maybe get some sod and lay it down. It's quick and easy. When it comes to seeding the grass, you can put down some grass seed, but you have to mind it every day. Put some type of cloth over the seeds so the birds don't eat up the seeds - yes they will! I used some old bed linen over the seeds until they sprout. The new grass needs water, water, water, especially with the harsh summer sun. It can be done, but you have be diligent. Don't mow the new grass until it reaches 4 inches in height. Mowing the grass will make it thicken up like a green carpet and the grass will choke out the weeds.

Ideally, the best time to seed the grass, it autumn, but go the the garden center ask what type of grass seed is best for you. Good luck.

Thank You All, you have been most helpful xx